Fungicides have well-known commercial value in protecting desirable plants from the development of fungal diseases. However, fungicides can be toxic to the plants to which they are applied as well as to beneficial organisms. Thus, it is desirable to maximize the efficacy of fungicides in order to minimize such detrimental effects on plants.
A wide variety of chemical compounds, differing in chemical structure, mechanism of activity, and preferred mode of application, are useful as fungicides. Exemplary types of chemical compounds useful as fungicides include chlorobenzenes and related compounds, quinones, dicarboximides, and systemic fungicides including sulphonamides, benzimidazoles, thiophanates, aminopyrimidines, piperazines, pyridines, imidazoles, and triazoles. These and other fungicidal compounds are described in R. J. Cremlyn, Agrochemicals, pp. 157-216, John Wiley & Sons, New York, N.Y. (1991).
The fungicide 1-[2-(2,4-dichlorophenyl)-2-(2-propenyloxy)ethyl]-1H-imidazole, known as Imazalil, is an imidazole fungicide. It is used, for example, to control powdery mildews in cucumbers, marrows and ornamentals, and Fusarium in seed potatoes. It is also used as a seed dressing for control of diseases in cereals such as, for example, Fusarium and Helminthosporium spp. Imazalil is also active against storage diseases, such as, for example, Penicillium, Gloeosporium, Phomopsis, and Phoma spp., of citrus fruit, pome fruit, bananas, and seed potatoes. Furthermore, Imazalil is active against benzimidazole-resistant strains of plant pathogenic fungi (The Pesticide Manual, Datix International Ltd., Bungay, Suffolk, The Bath Press, Bath, 1995).
Imazalil is presently used in its racemic form, and there is heretofore no reported use of a single enantiomer of Imazalil as a fungicide and no suggestion for such use. There remains a need for more highly effective fungicides with an improved balance between fungitoxicity and phytotoxicity. It is also desirable to reduce the costs associated with the use of fungicides. The present invention is directed to these, as well as other, important ends.